Cellulitis

From: http://www.nlm.nih.gov/medlineplus/ency/article/000855.htm

Causes
Staphylococcus and streptococcus bacteria are the most common causes of cellulitis.
The skin normally has many types of bacteria living on it. When there is a break in the skin, however, bacteria can enter the body and cause infection and inflammation. The skin tissues in the infected area become red, hot, irritated, and painful.

Risk factors for cellulitis include:
Cracks or peeling skin between the toes
History of peripheral vascular disease
Injury or trauma with a break in the skin (skin wounds)
Insect bites and stings, animal bites, or human bites
Ulcers from diabetes or a blockage in the blood supply (ischemia)
Use of corticosteroid medications or medications that suppress the immune system
Wound from a recent surgery

Symptoms
Fever
Signs of infection:
Chills, shaking
Fatigue
General ill feeling (malaise)
Muscle aches, pains (myalgias)
Warm skin, sweating
Pain or tenderness in the area with the rash or sore
Skin redness or inflammation that increases in size as the infection spreads
Skin sore or rash (macule):
Comes on suddenly
Grows quickly in the first 24 hours
Usually has sharp borders
Tight, glossy, "stretched" appearance of the skin
Warmth over the area of redness
Other symptoms that can occur with this disease:
Hair loss at the site of infection
Joint stiffness caused by swelling of the tissue over the joint
Nausea and vomiting

Exams and Tests
During a physical examination, the doctor may find:
Redness, warmth, and swelling of the skin
Swelling and drainage if the infection is around a skin wound
Swollen glands (lymph nodes) near the cellulitis
Your health care provider may mark the edges of the redness with a pen, to see if the redness goes past the marked border over the next several days.

Tests that may be used:
Blood culture
Complete blood count (CBC)

Treatment
Cellulitis treatment may require a hospital stay if:
You are very sick (very high temperature, blood pressure problems, nausea and vomiting that does not go away)
You have been on antibiotics and the infection is getting worse
Your immune system is not working well (due to cancer, HIV)
You have an infection around your eyes
Most of the time, treatment with oral antibiotics and close follow-up is enough. Treatment is focused on controlling the infection and preventing complications.

You may receive antibiotics to control the infection, and analgesics to control pain.
Raise the infected area higher than your heart to reduce swelling. Rest until your symptoms improve.

Outlook (Prognosis)
It is possible to be cured with 7 - 10 days of treatment. Cellulitis may be more severe in people with chronic diseases and those who are more prone to infection because their immune system is not working properly (immunosuppressed).
People with fungal infections of the feet may have cellulitis that keeps coming back. The cracks in the skin offer an opening for bacteria to get inside.

Possible Complications
Bone infection (osteomyelitis)
Inflammation of the lymph vessels (lymphangitis)
Meningitis (if cellulitis is on the face)
Sepsis, shock
Tissue death (gangrene)
When to Contact a Medical Professional
Call your health care provider if:

You have symptoms of cellulitis
You are being treated for cellulitis and you develop new symptoms, such as persistent fever, drowsiness, lethargy, blistering over the cellulitis, or red streaks that spread
Seek medical attention immediately if the cellulitis is on your face.

Prevention
Protect your skin by:

Keeping your skin moist with lotions or ointments to prevent cracking
Wearing shoes that fit well and provide enough room for your feet
Learning how to trim your nails to avoid harming the skin around them
Wearing appropriate protective equipment when participating in work or sports
Whenever you have a break in the skin:

Clean the break carefully with soap and water
Cover with a bandage and change it every day until a scab forms
Watch for redness, pain, drainage, or other signs of infection
Alternative Names
Skin infection - bacterial

Treatment of Cellulitis:
From 5 minutes consult

Medication (Drugs)
First Line
Treat 5–15 days or longer depending on clinical response and guided by culture results whenever possible. Use IV therapy for rapidly spreading infection or significant comorbidities.

Empiric therapy or mild cellulitis infection (activity against β-hemolytic streptococci and methicillin-susceptible S. aureus): Oral dicloxacillin, cephalexin, clindamycin, or IV cefazolin, oxacillin, or nafcillin (2)[A].
Parenteral therapy if severely ill or unable to tolerate oral therapy include penicillin-resistant penicillins, a 1st-generation cephalosporin, or if penicillin allergic use clindamycin or vancomycin (2)[A]
Necrotizing fasciitis and gas gangrene: Use parenteral clindamycin and penicillin (2)[B]
Recurrent infection underlying predisposing conditions, previous episode of proven MRSA infection, or systemic toxicity:
Use agents with activity against MRSA: Parenteral vancomycin or oral trimethoprim sulfamethoxazole (TMP/SMX), doxycycline or minocycline, or clindamycin (2)[B].
Mild early-suspected streptococcal etiology: Aqueous penicillin G, 600,000 U, then IM procaine penicillin at 600,000 U q8h–q12h (2)[B].
Freshwater exposure: Penicillinase-resistant penicillin plus gentamicin or fluoroquinolone (2)[B]
Saltwater exposure: Doxycycline 200 mg IV in divided doses (2)[C]
Human or animal bites: Oral amoxicillin-clavulanate or with IV ampicillin-sulbactam or ertapenem in patients. If mildly allergic to penicillin, use cefoxitin or carbapenems. For severe penicillin reactions, use doxycycline, TMP/SMX, or a fluoroquinolone plus clindamycin (2)[B].
Facial cellulitis in adults and children: (H. influenza B) Cefotaxime IV (1)[B]
Diabetic foot infection: Ampicillin/sulbactam 3g IV q6hr or imipenem/cilastatin, or meropenem. Alternative: Combinations targeting anaerobes as well as gram-positive and gram-negative aerobes
Severe infection, toxicity, immunocompromised patients, or worsening infection despite empirical therapy: Consider agents effective against MRSA (i.e., vancomycin, linezolid, tigecycline, quinupristin/dalfopristin, or daptomycin). Switch to oral dicloxacillin, cephradine, cephalexin, or cefadroxil when symptoms begin to resolve (3)[A].
Recurrent streptococcal cellulitis: Penicillin V 250 mg b.i.d. or if penicillin allergic, use erythromycin 250 mg once or twice daily (2)[B]

ALERT
Pediatric Considerations
Review contraindications, including patient allergies to antibiotics as well as organ failure.
Avoid doxycycline in children ≤8 years old and during pregnancy.
Now that children are HIB vaccinated, the most common predisposing conditions are conjunctivitis or an infected wound near the eye, rather than bacteremia (4)[A].

Second Line
Mild infection:
Penicillin allergy: Erythromycin 500 mg PO q6h
Cephalexin remains a cost-effective therapy for outpatient management of cellulitis at current estimated MRSA levels.

Additional Treatment
General Measures

Immobilization and elevation of the involved limb to reduce swelling may be needed in H. influenzae type B.
Sterile saline dressings to decrease local pain
Moist heat to localize the infection
Cool aluminum acetate compresses for pain relief
Compression stocking, pneumatic pumps, and when appropriate, diuretic therapy
Adjuvant corticosteroids (prednisone 0.5 mg/kg/d for 5–8 days) if partial response to parenteral antibiotics and hemorrhagic or bullous cellulitis (2)[B]
Treat intertrigo with topical antifungals (miconazole, clotrimazole, or terbinafine) (2)[B].

Surgery/Other Procedures
Debridement for gas and purulent matter collections
Intubation or tracheotomy may be needed for cellulitis of the head or neck.
Hand infections: Wide filleting incision in necrotizing cellulitis